This invention is directed to metal forming machines and, more particularly, to pyramid roll forming machines.
There are two basic types of pyramid roll forming machines extensively used by industrial organizations to contour parts. The first type is used to contour structural elements, such as stringers, ribs, stiffeners etc., and comprises a set of narrow, interchangeable, profiled rolls mounted on short shafts cantilevered from a drive housing. The second type is used to contour sheet metal and plate and comprises a set of long, cylindrical, rolls suspended between drive housings located at each end of the rolls. These elongate rolls are normally not changed, and must be of a diameter sufficient to keep roll deflection to a minimal amount under forming loads. This deflection restriction severely limits the capability of such machines to contour form in environments where the roll diameter cannot be allowed to exceed a maximum amount, e.g. 12 inches, because of the nature of the desired contour. The prior art, however, has overcome this restriction by providing an arrangement wherein reinforcing roll sets are arranged in a semi-planetary manner about small diameter work rolls. The semi-planetary reinforcing roll sets prevent the small diameter pyramid rolls from deflecting by an excessive amount. Regardless of the longitudinal length of the rolls (e.g., narrow for shaping structural elements or elongate for forming sheet and plate), all pyramid roll forming machines include three horizontally arrayed forming rolls that form a pyramid when viewed from an end. The pyramid includes two lower rolls and an upper roll having its axis located vertically above, and horizontally between, the axes defined by the lower rolls. Usually, the lower rolls are fixed in position and the upper roll is vertically movable.
As noted above, the rolls of pyramid roll forming machines designed to bend structural elements are relatively narrow. Contrawise the rolls of pyramid roll forming machines designed to bend relatively large sheets or plates are elongate and the position of the upper roll is controlled at both ends. In the past, jack screws, hydraulic cylinders and the like have been used to control the position of the upper forming rolls of such machines. Indicating dials, adjustable position stops and the like have been used in conjunction with such control subsystems to indicate and assist in controlling the position of the upper roll. Because of the high roll forces involved, these adjusting arrangements have been primarily designed for load carrying ability, rather than precision. As a result, part accuracy and process reliability have suffered.
Further, in the past, pyramid roll forming machines have been best suited for producing relatively simple curved parts. Specifically, under variable contoured parts have been produced using prior art pyramid roll forming machines, the technique used to control such machines to produce such parts has been costly, time consuming and unreliable. More specifically, in the past, variable contoured parts have been produced by prior art roll forming machines by frequently starting and stopping the rolls as the part has progressed through the machine. This start-stop action has been required on both narrow and elongate machines to allow the operator time to manually vary the position of the adjustable forming roll. Conical part contours (as opposed to cylindrical part contours) have been produced on elongate roll forming machines in a generally similar fashion, i.e., using a start-stop technique and manual adjustment at each end of the adjustable elongate roll. Obviously, manual roll adjustments are time consuming, whereby the resultant parts are expensive to produce. Moreover, it is extremely difficult, and in many cases impossible, to reliably manually reproduce the position of the adjustable forming roll when more than one part is to be formed. As a result, usually, expensive contoured templates or gauges must be formed for the operator's use. And, frequently, multiple roll passes must be made before the desired contour is achieved.
Even more importantly, in the past, the productivity of prior art pyramid roll forming machines has been relatively low, particularly when the machines are used to create only a small number of each of a variety of different parts; even through the parts are similar and, a start-stop technique is not required. Low productivity is a direct result of the prior art requirement that the vertical position of the upper roll be manually adjusted prior to each different part being formed.
Therefore, itis an object of this invention to provide a method of and apparatus for improving the flexibility and capability of pyramid roll forming machines.
It is a further object of this invention to provide a method of and apparatus for improving the versatility and productivity of pyramid roll forming machines.
It is another object of this invention to provide a new and improved pyramid roll forming machine suitable for forming a wide variety of part contours and shapes.
It is a still further object of this invention to provide a new and improved pyramid roll forming machine adapted to create cylindrical, elliptical, conical and varying conical parts.
It is a still further object of this invention to provide a numerical control method of operating a pyramid roll forming machine.